Structure for mounting batteries onto electric vehicles

ABSTRACT

A structure for mounting a battery onto an electric vehicle comprises: a pair of first body members extending in a longitudinal direction of the electric vehicle; a second body member, which connects the pair of first body members, extending in transversal direction of the electric vehicle; a battery case, which contains a battery, disposed between the pair of first body members and rear of the second body member; a plurality of first supporting members, which connect between the pair of first body members, fixed on a bottom of the battery case; and a second supporting member connecting between one of the first supporting members, which is disposed in the forefront of the battery case.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a structure for mounting a battery onto an electric vehicle.

(2) Description of Related Art

Structures for mounting batteries onto electric vehicles have been known in the art. The following related document 1 discloses an example of such a structure.

In the related document 1, as shown in FIG. 1, a battery (16) is fixed to a rear seat cross member (7), a battery cross member (11), side sills (3) and rear side members (9) by a battery mounting frame (17).

-   [Related Document 1] Japanese Laid-open Publication H06-32247

However, by the technique of the related document 1, the battery mounting frame (17) is formed in a grille shape, and thus increased weight and cost of the electric vehicle are unavoidable.

SUMMARY OF THE INVENTION

The present invention has been developed in consideration of this situation, and it is therefore an object of the invention to provide a structure for mounting a battery onto an electric vehicle to improve the crash-resistant capability of the battery mounted on the electric vehicle while preventing increased weight and cost.

For this purpose, in accordance with an aspect of the present invention, there is provided a structure for mounting the battery onto the electric vehicle comprising: a pair of first body members (11 and 11) extending in a longitudinal direction of the electric vehicle (10); a second body member (12), which connects the pair of first body members (11 and 11), extending in transversal direction of the electric vehicle (10); a battery case (13), which contains a battery (20), disposed between the pair of first body members (11 and 11) and rear of the second body member (12); a plurality of first supporting members (61A, 61B, 61C and 61D), which connect between the pair of first body members (11 and 11), fixed on a bottom of the battery case (13); and a second supporting member (62A and 62B) connecting between the second body member (12) and one of the first supporting members (61A) which is disposed in the forefront of the battery case (13).

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantages thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein:

FIG. 1 is a top view schematically showing the entire configuration of an embodiment of the present invention;

FIG. 2 is a side view schematically showing the entire configuration of the embodiment of the present invention;

FIG. 3 is a top view schematically showing a battery tray in the embodiment of the present invention;

FIG. 4 is a schematic perspective view mainly showing batteries in a battery case and a battery fastener in the embodiment of the present invention;

FIG. 5 is a schematic perspective view mainly showing metal frames built into a battery tray in the embodiment of the present invention;

FIG. 6 (A) is a top view schematically showing a built-in nut in the embodiment of the present invention;

FIG. 6 (B) is a side view schematically showing the same built-in nut in the embodiment of the present invention;

FIG. 6 (C) is a bottom view schematically showing the same built-in nut in the embodiment of the present invention;

FIG. 7 is a cross-section view schematically showing the same built-in nut in the embodiment of the present invention;

FIG. 8 is a perspective bottom view schematically showing the bottom side of the battery case in the embodiment of the present invention;

FIG. 9 is a perspective view schematically showing the bottom side of the battery case in the embodiment of the present invention;

FIG. 10 is a schematic view showing lateral-end supporting members and a front-end supporting member in the embodiment of the present invention;

FIG. 11 is a cross-section view indicated XI-XI in FIG. 1 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 12 is a cross-section view indicated XII-XII in FIG. 1 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 13 is a cross-section view indicated XIII-XIII in FIG. 1 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 14 is a cross-section view indicated XIV-XIV in FIG. 1 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 15 is a front view schematically showing a cover plate in the embodiment of the present invention;

FIG. 16 is a perspective view schematically showing the cover plate in the embodiment of the present invention;

FIG. 17 is a cross-section view indicated XVII-XVII in FIG. 16 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 18 is a cross-section view indicated XVIII-XVIII in FIG. 16 schematically showing a part of the structure in the embodiment of the present invention;

FIG. 19 is a perspective view schematically showing a battery cover in the embodiment of the present invention;

FIG. 20 is a top view schematically showing the battery cover in the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiment of the present invention will now be described with reference to the accompanying drawings.

As shown in FIG. 1, side members (also called ‘body members’ or ‘first body members’) 11 and 11 are mounted on the left and right sides of an electric vehicle 10. The side members 11 and 11 extend in the longitudinal direction of the electric vehicle 10.

Further, a battery cross member (also called ‘body member’ or ‘second body member’) 12, which extends in the transversal direction (left-right direction) and which connects the pair of side members 11 and 11, is also mounted in the electric vehicle 10.

The side members 11 and 11 and the battery cross member 12 are iron, and constitute a body of the electric vehicle 10.

At a position between the pair of side members 11 and 11 and rear of the battery cross member 12, a battery case 13 is disposed. The battery case 13, which is made from polybutylene resin including glass fibers, contains and holds batteries 20 (shown in FIG. 4) inside thereof while avoiding ventilation between outside and inside by keeping the inside of battery case 13 airtight.

As shown in FIG. 2, the battery case 13 mainly comprises a battery tray 14 and a battery cover 15.

As shown in FIG. 3, a front-end wall 16, a left-end wall 17, a right-end wall 18, a rear-end wall 19, a front partition 21, a middle partition 22 and a rear partition 23 are fixed in the battery tray 14.

The front partition 21, the middle partition 22 and the rear partition 23 are walls extending between the left-end wall 17 and the right-end wall 18 in the left-right direction of the battery tray 14.

The front partition 21 is disposed at the front of the middle partition 22. The rear partition 23 is disposed at the rear of the middle partition 22.

Further, in the battery tray 14, front-battery partitions 24A, 24B, 24C and 24D are fixed. The front-battery partitions 24A, 24B, 24C and 24D are walls extending between the front-end wall 16 and the front partition 21 in the longitudinal direction (front-rear direction).

Furthermore, in the battery tray 14, rear-battery partitions 27A, 27B, 27C and 27D are fixed. The rear-battery partitions 27A, 27B, 27C and 27D are walls extending between the front partition 21 and the rear partition 23 in the front-rear direction.

Still further, in the battery tray 14, front reinforcing walls 25A and 25B and concave side walls 29 and 29 are formed. The front reinforcing walls 25A and 25B are walls extending between the front partition 21 and the middle partition 22 in the front-rear direction. The concave side walls 29 and 29 are walls to individually make concave portions 28A and 28B.

Between the rear partition 23 and the middle partition 22, middle-battery partitions 26A and 26B are formed which walls extend in the front-rear direction.

Further, between the middle-battery partitions 26A and 26B, rear reinforcing walls 31A and 31B are formed which walls extend in the front-rear direction.

As shown in FIG. 4, batteries 20 are fixed securely inside the battery case 13 in such a way that after the batteries 20 are individually disposed at the correct positions on the battery tray 14, the batteries 20 are supported by battery holders (not shown), then the battery holders are fixed to the battery tray 14 by bolts (not shown).

As shown in FIG. 5, in the battery tray 14, a frame set (also called ‘metal frame’) 32 is included. The frame set 32, which is made from iron, mainly comprises front frame set 33 and rear frame set 34.

The front frame set 33 comprises a front-left frame 38, a front-middle frame 36 and a front-right frame 37.

The front-left frame 38 is an L-shaped part. On a left surface of the front-left frame 38, nuts 38A, 38B, 38C and 38D are welded. Further, on a front surface of the front-left frame 38, a nut 38E is welded. The front-left frame 38 is embedded in the left-end wall 17 and the front-end wall 16 of the battery tray 14 as shown in FIG. 3.

Likewise, the front-right frame 37 shown in FIG. 5 is an L-shaped part. On a right surface of the front-right frame 37, nuts (not shown) are welded. Further, on a front surface of the front-right frame 37, a nut 37E is welded. The front-right frame 37 is embedded in the right-end wall 18 and the front-end wall 16 of the battery tray 14 shown in FIG. 3.

The front-middle frame 36 shown in FIG. 5 is a U-shaped part. On the front surface of the front-middle frame 36, two nuts 36A and 36B are welded.

Additional plates 39A and 39B, which are parts of the front-middle frame 36, extend in the front-rear direction. The additional plate 39A is embedded in the front-battery partition 24A, which is disposed between imaginary lines L₁ and L₂ and extends rearward from a front block (also called ‘first crash-proof block’) 63A shown in FIG. 3. Likewise, the other additional plate 39B is embedded in the front-battery partition 24D, which is disposed between imaginary lines L₃ and L₄ extending rearward from another front block (also called ‘first crash-proof block’) 63B. A front wall 36C, which is a part of the front-middle frame 36, extends in the left-right direction. The front wall 36C is embedded in the front-end wall 16. Into the nuts 38A, 38B, 38C, 38D, 38E and 37E, bolts 67 are fitted.

The rear frame set 34 shown in FIG. 5 comprises a rear-lateral-left frame 41, a rear-end-left frame 42, a rear-end-middle frame 43, a rear-end-right frame 44 and a rear-lateral-right frame 45.

The rear-lateral-left frame 41 is a part embedded in the left-end wall 17 shown in FIG. 3. On a left surface of the rear-lateral-left frame 41, nuts 41A, 41B, 41C and 41D are welded.

Likewise, the rear-lateral-right frame 45 shown in FIG. 5 is embedded in the right-end wall 18 shown in FIG. 3. On a right surface of the rear-lateral-right frame 45 four nuts (not shown) are welded.

As shown in FIG. 5, the rear-end-left frame 42, the rear-end-middle frame 43 and the rear-end-right frame 44 are embedded in the rear-end wall 19 shown in FIG. 3.

Between the front-left frame 38 and the front-middle frame 36, gap G₁ is formed. Between the front-right frame 37 and the front-middle frame 36, gap G₂ is formed. Further, between the rear-lateral-left frame 41 and the rear-end-left frame 42, gap G₃ is formed. Still further, between the rear-end-left frame 42 and the rear-end-middle frame 43, gap G₄ is formed. Furthermore, between the rear-end-middle frame 43 and the rear-end-right frame 44, gap G₅ is formed. Still furthermore, between the rear-end-right frame 44 and the rear-lateral-right frame 45, gap G₆ is formed.

A built-in nut 51 shown in FIGS. 6 (A), (B), (C) and FIG. 7 is embedded in the battery tray 14.

The iron built-in nut 51 comprises an upper nut 52, a middle stem 53 and a lower nut 54.

The upper nut 52 is a cylindrical part which extends in the vertical direction and has an upper opening 52A which opens upwardly. Inside the upper nut 52, a bolt groove 52B is formed.

The lower nut 54 is identical to the upper nut 52 except that the upper nut 52 is in an upside-down position. In other words, the lower nut 54 is also a cylindrical part which extends in the vertical direction and has a lower opening 54A which opens downwardly. Inside the lower nut 54, a bolt groove 54B is formed.

The middle stem 53 is a cylindrical part between the upper nut 52 and the lower nut 54. On the surface of the middle stem 53, a plurality of notches (serrated portion) 53A are formed.

Between the upper nut 52 and the middle stem 53, an upper constriction 55A is formed. Also, between the middle stem 53 and the lower nut 54, a lower constriction 55B is formed.

The upper constriction 55A and the lower constriction 55B are cylindrical parts whose outer diameter (second diameter) D₂ is smaller than the outer diameter (first diameter) D₁ of the upper nut 52, the lower nut 54 and the middle stem 53.

Because of the serrated portion 53A formed on the middle stem 53, it is possible to avoid loosening and spinning of the built-in nut 51 embedded in the battery tray 14 even if a rotational torque is inputted to the built-in nut 51 around the center axis C₅₁.

Further, according to the upper constriction 55A and the lower constriction 55B, it is possible to avoid the built-in nut 51 dropping from the battery tray 14 even if the force is inputted to the built-in nut 51 along the direction of the center axis C₅₁.

As shown in FIG. 8 and FIG. 9, lateral-end supporting members (also called ‘supporting members’ or ‘first supporting members’) 61A, 61B, 61C and 61D are fixed to the bottom surface 14A of the battery tray 14.

The lateral-end supporting member 61A is disposed at the front row called an A-supporting member 61A. The lateral-end supporting member 61B disposed rear of the A-supporting member 61A is called a B-supporting member 61B.

Further, the lateral-end supporting member 61C disposed rear of the B-supporting member 61B is called a C-supporting member 61C. Likewise, the lateral-end supporting member 61D disposed rear of the C-supporting member 61C is called a D-supporting member 61D.

As shown in FIG. 1, each of the lateral-end supporting members 61A, 61B, 61C and 61D extends in the transversal direction connecting between the side members 11 and 11 to support the bottom surface 14A. The lateral-end supporting members 61A, 61B, 61C and 61D are made from iron.

As shown in FIG. 8, on the A supporting member 61A, front-end supporting members (also called ‘supporting members’ and ‘second supporting members’) 62A and 62B are fixed. Each of the front-end supporting members 61A and 62B is a part which extends in the

As shown in FIG. 2, the lateral crash-proof blocks 66A, 66B, 66C and 66D, which connect between side member 11 and the battery case 13, are respectively disposed between the bottom surface of the side member 11 and the lateral-end supporting members 61A, 61B, 61C and 61D. Each of the lateral crash-proof blocks 66A, 66B, 66C and 66D is made from iron and is a hollow square pillar in shape.

As shown in FIG. 10, the front-end supporting members 62A and 62B are only connected to the A-supporting member 61A and are not connected to the B-supporting member 61B, C-supporting member 61C and D-supporting member 61D (see ‘X’ in FIG. 10).

As shown in FIG. 1, the front-end supporting members 62A and 62B connect between the battery cross member 12 and A-supporting member 61A via front blocks 63A and 63B which will be described just below. In addition, the front-end supporting members 62A and 62B are made from iron.

On the front-end supporting members 62A and 62B, each of the front blocks (also called ‘crash-proof blocks’ or ‘first crash-proof blocks’) 63A and 63B is welded respectively. The front blocks 63A and 63B are fixed to the front-end wall 16 by bolts 64 (shown in FIG. 8) and are fixed to the battery cross member 12 by bolts 65 (shown in FIG. 1).

In other words, the front blocks 63A and 63B are parts which individually connect between the battery cross member 12 and the A-supporting member 61A and are disposed between the battery cross member 12 and the battery tray 14. Further, the front blocks 63A and 63B are made from iron.

As shown in FIG. 1, the lateral crash-proof blocks (also called ‘crash-proof blocks’ or ‘second crash-proof blocks’) 66A, 66B, 66C and 66D are respectively welded on both ends of each of the lateral-end supporting members 61A, 61B, 61C and 61D

The lateral crash-proof block 66A fixed on the A-supporting member 61A is called an A-lateral crash-proof block 66A. The lateral crash-proof block 66B fixed on the B-supporting member 61B is called a B-lateral crash-proof block 66B. The lateral crash-proof block 66C fixed on the C-supporting member 61C is called a C-lateral crash-proof block 66C. The lateral crash-proof block 66D fixed on the D-supporting member 61D is called a D-lateral crash-proof block 66D.

As shown in FIG. 8, the lateral crash-proof blocks 66A, 66B, 66C and 66D are fixed to the left-end wall 17 and the right-end wall 18 of the battery tray 14 by bolts 67, and are fixed to the side members 11 and 11 by bolts 68 as shown in FIG. 1.

As shown in FIG. 2, the lateral crash-proof blocks 66A, 66B, 66C and 66D, which connect between side member 11 and the battery case, are respectively disposed between the bottom surface of the side member 11 and the lateral-end supporting members 61A, 61B, 61C and 61D. Each of the lateral crash-proof blocks 66A, 66B, 66C and 66D is made from iron and is a hollow square pillar in shape.

Further, each of the A-lateral crash-proof block 66A and the B-lateral crash-proof block 66B is directly fixed to the side member 11, where as, as shown in FIG. 2, the C-lateral crash-proof block 66C is fixed to the side member 11 via a C-connecting block 69C. Also, the D-lateral crash-proof block 66D is fixed to the side member 11 via a D-connecting block 69D.

Although the side member 11 is extended from a point (shown as an arrow A in FIG. 2) backwardly and upwardly, the battery tray 14 is kept in a horizontal position because the C-connecting block 69C is interposed between the side member 11 and the C supporting member 61C, also the D-connecting block 69D is interposed between side member 11 and the D supporting member 61D.

As shown in FIG. 11, the A-supporting member 61A is fixed by the bolt 68 engaged with a cap nut 11B mounted in the reinforcing member 11A of the side member 11. The B-supporting member 61B is also fixed to the side member 11 by the structure shown in FIG. 11, description of which is omitted in the drawings.

As shown in FIG. 12, the C-supporting member 61C is connected to the side member 11 via the C-connecting block 69C. The C-connecting block 69C is a hollow iron part in which a cap nut 11C is mounted. The C-supporting member 61C is fixed to the C-connecting block 69C by the bolt 68 engaged with the cap nut 11C.

As shown in FIG. 13, the D-supporting member 61D is connected to the side member 11 via the D-connecting block 69D. The D-connecting block 69D is a hollow iron part. The D-supporting member 61D is fixed to the side member 11 by the bolt 68 engaged with the cap nut 11D mounted in the side member 11.

Further, a nut 69D, is welded on the bottom of the D-connecting block 69D. The D-supporting member 61D is fixed to the D-connecting block 69D by a bolt 71 which engages with the nut 69D₁.

As shown in FIG. 9, between the left-end wall 17 of the battery tray 14 and the side member 11 and between the right-end wall 18 of the battery tray 14 and the side member 11, two high-voltage cables 72 are respectively disposed. The high-voltage cables 72, which are capable of carrying about 300V, connect between the batteries 20 mounted in the battery case 13 and an inverter (also called ‘external device) not shown in the drawings.

Each of the high-voltage cables 72 has a hole connector 73 connected to an electric-output socket (not shown) in the battery case 13.

At both the lateral surface of the battery tray 14 facing the side members 11 (namely, at the left-end wall 17 and the right-end wall 18) and the bottom surface 14A of the battery tray 14, dent portions 28A and 28B are formed.

Each of the dent portions 28A and 28B has a concave side wall 29, which extends parallel to the side member 11, a concave front wall 74, which extends from the front end of the concave side wall 29 in the lateral direction, and a concave rear wall 75, which extends from the rear end of the concave side wall 29 in the lateral direction.

Further, as shown in FIG. 14, casing bolt-hole portions 76, a casing low-voltage cable hole portion 77, a casing center-hole portion 78 and a casing high-voltage cable hole portion (cable hole portion) 79 are formed at the concave side wall 29.

A cover plate 81 shown in FIG. 15 is fixed on the back surface of the concave side wall 29. Cover plate 81 will be described below in detail.

Each of the casing bolt-hole portions 76 shown in FIG. 14 is a hole through which a plate fixing bolt (not shown) is engaged with a plate bolt-hole portion 82 formed on the cover plate 81

Low-voltage cables 89 (shown in FIG. 16) used for supplying about 12V electric power to electrical equipment pass through the casing low-voltage cable hole portion 77. Further, the casing low-voltage cable hole portion 77 communicates with a plate low-voltage cable hole portion 83.

The casing center hole portion 78 communicates with a venting hole 84 formed at the cover plate 81.

High-voltage cable 72 (shown in FIG. 9) passes through each of the casing high-voltage cable hole portions 79 and 79. The casing high-voltage cable hole portions 79 and 79 respectively communicate with plate high-voltage cable hole portions 85A and 85B formed at the cover plate 81.

Further, each concave side wall 29 is kept at a distance L₅ (shown in FIG. 9) defined based on the outer diameter D₃ of the high-voltage cable 72 from the side member 11.

The greater the outer diameter D₃ (thickness) of the high-voltage cable 72, the greater distance L₅ between the concave side wall 29 and the side member 11 becomes to permit bending of cable 72. Conversely, the smaller outer diameter D₃, the shorter distance L₅ may be.

As shown in FIG. 15, the cover plate 81 is fixed to the back surface of concave side wall 29 of the battery tray 14. The cover plate 81 is a plate made from aluminum covering the casing bolt-hole portions 76, the casing low-voltage cable hole portion 77, the casing center hole portion 78 and the casing high-voltage cable hole portions 79 as discussed with reference to FIG. 14.

Aluminum is used for cover plate 81 because both rigidity and weight saving are required, and it is also necessary to avoid detachment between the cover plate 81 and battery tray 14 even if the resin material of battery tray 14 expands or contracts due to temperature variation.

One point the inventors have focused attention on is that the linear expansion coefficients of the main material of the battery tray 14 which is polybutylene resin including glass fiber and the material of the cover plate 81 which is aluminum, are almost the same, and accordingly, the cover plate 81 is made from aluminum.

At the cover plate 81, the plate bolt-hole portions 82, the plate low-voltage cable hole portion 83, the venting hole 84 and the plate high-voltage hole portions (cable hole portions) 85A and 85B are formed.

Each of the plate bolt-hole portions 82 is a hole in which each of the plate fixing bolts 104 shown in FIG. 17 are engaged.

The plate bolt-hole portions 82 open to the front side (near side in FIG. 15) of the cover plate 81. However, the plate bolt-hole portions 82 do not open to the back (far side in FIG. 15) of the cover plate 81. Consequently, the cover plate 81 is not penetrated by the plate bolt-hole portions 82.

In the plate low-voltage cable hole portion 83, as shown in FIG. 16, a rubber cap 88 is fitted. The low-voltage cables 89 are inserted through the rubber cap 88.

The venting hole 84 is a hole for venting air from the battery case 13 when the air pressure increases in the battery case 13. In venting hole 84, a one-way valve (not shown) is fitted, thereby maintaining airtightness in the battery case 13.

As shown in FIG. 15 and FIG. 18, each of the plate high-voltage cable hole portions 85A and 85B is a hole into which individual socket ends 101A and 101A of cable holders 101 and 101 are inserted. The plate high-voltage cable hole portions 85A and 85B are respectively communicated with the casing high-voltage cable hole portions 79 and 79 shown in FIG. 14.

Into the cable holders 101 and 101, each of the high-voltage cables 72 and 72 is individually inserted. Each of the socket ends 101A and 101A of the cable holders 101 and 101 has a rubber O-shaped ring 103 individually equipped to secure airtightness in the battery case 13.

The cable holders 101 and 101 are fixed to the cover plate 81 by holder fixing bolts 102 and 102, respectively. The holder fixing bolts 102 and 102 are bolts which are individually engaged with cable holder hole portions 86A and 86B.

The cable holder hole portions 86A and 86B are holes which are respectively formed adjacent to the plate high-voltage cable hole portions 85A and 85B. The cable holder hole portions 86A and 86B open to the front side of the cover plate 81 and do not open to the back side of the cover plate 81.

The inner surface of each of the plate high-voltage cable hole portions 85A and 85B is mirror finished so that the O-shaped ring 103 fits each of the plate high-voltage cable hole portions 85A and 85B without leaving a gap.

Further, because of the mirror finished inner surface, it is possible to protect the O-shaped ring 103 from any damage when the O-shaped ring 103 is inserted into each of the plate high-voltage cable hole portions 85A and 85B.

Additionally, a sealing groove 87 is formed around the outer edge of the cover plate 81. Sealing agent (not shown) is filled into sealing groove 87 to avoid leaving a gap between the concave side wall 29 of the battery tray 14 and the cover plate 81 as shown in FIG. 17.

As shown in FIG. 19 and FIG. 20, the battery cover 13 has a front raised portion 91, a middle raised portion 92 and a rear raised portion 93.

The front raised portion 91 is a portion which is raised near the front end of the battery cover 13. The rear raised portion 93 is a portion which is raised near the rear end of the battery cover 13. On the front raised portion 91, a maintenance hole portion 94 is formed.

The maintenance hole portion 94 is formed for maintaining inside the battery case 13 and is normally covered by a covering plate (not shown).

The middle raised portion 92 is a portion which is raised between the front raised portion 91 and the rear raised portion 93, however, the middle raised portion 92 is lower than the front raised portion 91 and the rear raised portion 93 in height.

A flange 95, on which cover bolt hole portions 96 are formed, is formed around the edge of the battery cover 13.

As shown in FIG. 3, tray bolt hole portions 105, corresponding to the location of the cover bolt hole portions 96, are formed on the front-end wall 16, the left-end wall 17, right-end wall 18, and rear-end wall 19 of the battery tray 14 (namely, around the edge of battery tray 14).

According to this arrangement, the cover bolt hole portions 96 and the tray bolt hole portions 105 respectively communicate with each other when the battery cover 15 is put on the battery tray 14. Thus, it is allowed that bolts (not shown) are individually inserted into the cover bolt hole portions 96 and the tray bolt hole portions 105 to fix the battery tray 14 and the battery cover 15.

Namely, the embodiment of the present invention can provide the following effects or/and advantages.

For example, if the front side of the electric vehicle 10 is crashed, the battery case 13 containing batteries 20 moves forward due to inertia. Particularly, the batteries 20 are comparatively heavy, therefore, it is impossible to omit kinetic energy of the battery case 13 when the electric vehicle 10 is crashed.

However, according to the present invention in this embodiment, it is possible to avoid the battery case 13 moving forward and being crashed against the battery cross member 12 because the lateral-end supporting members 61A, 61B, 61C and 61D and the front-end supporting members 62A and 62B are provided.

Namely, it is possible to maintain the gap (see G_(F) in FIG. 1) between the battery case 13 and the battery cross member 12 even if the electric vehicle 10 is crashed, and therefore, it is possible to avoid damage to cables (not shown) installed in the gap G_(F) so that the reliability of the electric vehicle 10 is improved.

The front-end supporting members 62A and 62B are not connected to all of the lateral-end supporting members 61A, 61B, 61C and 61D, however, the front-end supporting members 62A and 62B are connected to only the lateral-end supporting member 61A which is disposed at the front row. Accordingly, it is possible to reduce the length of the front-end supporting members 62A and 62B, and therefore, it is possible to suppress the weight and cost of front-end supporting members 62A and 62B.

Namely, it is possible to improve crash-resisting capability of the batteries 20 mounted on the electric vehicle 10 while preventing increased weight and cost.

Further, the lateral-end supporting members 61A, 61B, 61C and 61D and front-end supporting members 62A and 62B are made from iron. In addition, the battery case 13 is made from polybutylene resin including glass fibers. According to this arrangement, it is possible to reduce the weight of the battery case 13 at a reasonably low cost in mass production. Further, it is also possible to improve the mounting stiffness of the battery case 13 in relation to the electric vehicle 10.

The battery case 13 containing the batteries 20 is robustly supported by the lateral-end supporting members 61A, 61B, 61C and 61D, and further, the front blocks 63A and 63B prevent collision of the battery case 13 with the battery cross member 12 if the battery case 13 moves forward due to inertia even if the front side of the vehicle 10 is crashed.

Further, the lateral crash-proof blocks 66A, 66B, 66C and 66D are inserted between the side surface of the battery case 13 and the side member 11, and accordingly, it is possible to avoid a collision of the battery case 13 with the side member 11 if the battery case 13 moves laterally due to inertia even if the lateral side of the vehicle 10 is crashed.

Namely, it is possible to keep the gap (see G_(s) and G_(s) in FIG. 1) between the battery case 13 and the side members 11 even if the electric vehicle 10 is crashed, therefore, it is possible to prevent damage of the high-voltage cables 72 and low-voltage cables 89 installed in the gap G_(s) and G_(s) so that the reliability of the electric vehicle 10 is improved.

Additionally, the lateral-end supporting members 61A, 61B, 61C and 61D and front-end supporting members 62A and 62B and battery cross member 12 are made from iron. Further, the battery case 13 is made from polybutylene resin including glass fibers.

According to this arrangement, it is possible to reduce the weight of the battery case 13 at a reasonably low cost in mass production. Further, it is also possible to improve the mounting rigidity of the battery case 13 on the electric vehicle 10.

The front-end supporting members 62A and 62B and the battery cross member 12 are connected via the front blocks 63A and 63B. Further, the lateral-end supporting members 61A, 61B, 61C and 61D and the side members 11 are connected via the lateral crash-proof blocks 66A, 66B, 66C and 66D. According to this arrangement, it is possible to lower the center of gravity of the battery case 13 containing the heavy batteries 20.

Further, due to inserting the front blocks 63A and 63B between the battery case 13 and the battery cross member 12 and inserting the lateral-end supporting members 61A, 61B, 61C and 61D between the battery case 13 and the side members 11, it is possible to avoid collision with the cross member 12 or the side member 11 if the battery case 13 moves due to inertia even if the vehicle 10 is crashed.

Therefore, it is possible to improve the crash-resistant capability of the batteries 20 mounted on the electric vehicle 10.

Namely, if the front side of the electric vehicle 10 is crashed, it is possible to avoid collisions with the battery cross member 12 if the battery case 13 moves forward due to inertia. Likewise, if the lateral side of the electric vehicle 10 is crashed, it is possible to avoid collision with the side members 11 if the battery case 13 moves laterally due to inertia.

As discussed previously with FIG. 9, the high-voltage cables 72 and 72 are individually inserted into the plate high-voltage cable hole portions 85A and 85B formed at the cover plates 81 respectively fixed on the dent portions 28A and 28B of the battery case 13. Further, the high-voltage cables 72 and 72, which are disposed between the side members 11 and the battery case 13, are curved in an arc shape with a bending radius.

Further, each of the concave side walls 29 of the dent portions 28A and 28B is distanced L₅, which is defined corresponding to the outer diameter D₃ of the high-voltage cable 72, from the side member 11. Accordingly, it is possible to avoid damaging the high-voltage cables 72 due to bending the high-voltage cables 72 with excessively small radius and it is also possible to avoid wasting the space in the battery case 13 due to curving the high-voltage cables 72 with excessively large radius.

In other words, it is possible to easily install the high-voltage cables 72 connected to the batteries 20 mounted on the electric vehicle 10 while utilizing limited space in the electric vehicle 10

Further, the high-voltage cables 72 are connected to the batteries 20 in the battery case 13 via the hole connectors 73, and accordingly, it is possible to secure the connection between the high-voltage cables 72 and the batteries 20 at a lower cost.

Particularly, it is possible to avoid unwanted disconnection of the high-voltage cables 72 from the cables 72 due to using the hole connectors 73 to connect between the batteries 20 and the high-voltage batteries 20 as compared with using conventional detachable connectors.

Therefore, it is possible to improve the reliability of the electric vehicle 10 by preventing accidental disconnection between the high-voltage cables 72 and the batteries 20.

Further, it is possible to reduce cost and weight of the electric vehicle 10 by using the hole connectors 73 as compared with using conventional detachable connectors.

Each of the high-voltage cables 72 is drawn from inside the battery case 13 through the plate high-voltage cable hole portions 85A and 85B formed at the aluminum cover plate 81, and accordingly, it is possible to avoid excessively varying the inner diameter of the plate high-voltage cable hole portions 85A and 85B due to variation of air temperature.

Further, it is possible to avoid external air flowing into the battery case 13 due to sealing by each O-shaped ring 103 between the outer surface of the high-voltage cables 72 and 72 and the inner surface of the plate high-voltage cable hole portions 85A and 85B.

Additionally, although the plate bolt-hole portions 82 open to the front side of the cover plate 81, the plate bolt-hole portions 82 do not open to the back side of the cover plate 81, and accordingly, it is possible to secure the airtightness in the battery case 13 while allowing the plate fixing bolts 104, for fixing the cover plate 81 to the battery case 13, to be engaged with the plate bolt-hole portions 82.

As shown in FIG. 6 and FIG. 7, portions whose outer diameter is locally small (second diameter D₂) at the built-in nut 51, namely, the upper constriction 55A and the lower constriction 55B in which resin of battery tray 14 is entered. Accordingly, it is possible to avoid the built-in nut 51 dropping from the battery tray 14 even if force is vertically inputted to the built-in nut 51.

Further, due to the serrated portion 53A formed on the middle stem 53, it is possible to avoid spinning of the built-in nut 51 embedded in the battery tray 14 even if torque is inputted to the built-in nut 51 to rotate the built-in nut 51 around the center axis C₅₁, accordingly, it is possible to surely engage the bolt (not shown) with the built-in nut 51.

The present invention is not limited to the above embodiment, but covers all changes and modifications which do not constitute departures from the spirit and scope of the invention.

From the invention thus described, the same may be varied in many ways. Such variations are not be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following clams. 

1. A structure for mounting a battery onto an electric vehicle comprising: a pair of first body members extending in a longitudinal direction of the electric vehicle; a second body member, which connects said pair of first body members, extending in transversal direction of the electric vehicle; a battery case, which contains a battery, disposed between said pair of first body members and rear of said second body member; a plurality of first supporting members attached to a bottom of said battery case, each of said plurality of first supporting members being a plate-shaped member being provided independently from one another and extending across said battery case between said pair of first body members, and protruding from both sides of said battery case toward said pair of first body members, such that a first end of a first supporting member is attached to one of said pair of first body members and a second end, opposite to the first end, is attached to another one of said pair of first body members; and a second supporting member attached to the bottom of said battery case and extending in the longitudinal direction of the electric vehicle toward said second body member from a first supporting member disposed closest to said second body member beyond a front-end wall of said battery case without making a direct contact with said second body member; and a crash-proof block attached to an upper surface of said second supporting member at a portion that extends beyond the front-end wall of said battery case, a rear end of said crash-proof block being attached to the front-end wall of said battery case, and a front end of said crash-proof block being attached to said second body member.
 2. The structure for mounting the battery onto the electric vehicle according to claim 1 wherein said first supporting members and said second supporting member are made of metal, and said battery case is made of resin.
 3. The structure for mounting the battery onto the electric vehicle according to claim 1 wherein said a battery case includes a battery tray on which a battery is placed, and a battery cover that covers the battery tray, said battery case includes a at least one concave portion at a bottom thereof that defines a concave side wall through which a power cable attached to the battery extends to the outside of the battery case, such that the power cable extends inside the concave portion.
 4. The structure for mounting the battery onto the electric vehicle according to claim 3 further comprising: a cover plate attached to the concave side wall, the cover plate having cable hole portions through which the power cable passes.
 5. The structure for mounting the battery onto the electric vehicle according to claim 4, wherein said battery case is made of resin, and said cover plate is made of aluminum.
 6. The structure for mounting the battery onto the electric vehicle according to claim 1, wherein said second supporting member projects forward from a front end of said battery case.
 7. The structure for mounting the battery onto the electric vehicle according to claim 1, wherein said crash-proof block is welded to the upper surface of said second supporting member.
 8. The structure for mounting the battery onto the electric vehicle according to claim 1, wherein the rear end of said crash-proof block is bolted onto the front-end wall of said battery case.
 9. The structure for mounting the battery onto the electric vehicle according to claim 1, wherein the front end of said crash-proof block is bolted to said second body member. 